Canary Weighted Consistent Hashing

[2339478391]

Weighted Consistent Hashing

consider that
1.route 30% requests to canary backends just like what canary-weight did
2.the requests of a single user/device route to primary backends or canary backends randomly, it cause unconsistency
3.we want a single user routes to primary backends or canary backends all the time during the lifecycle

Add two new canary annotations
canary-consistency
it has two option, "header" or "cookie", means

header="userId" value="1" this userId routes to primary backends all the time
header="userId" value="2" this userId routes to canary backends all the time
or
cookie="userId" value="1" this userId routes to primary backends all the time
cookie="userId" value="2" this userId routes to canary backends all the time

canary-hash-seed
it's optional, it makes sure two experiments requests are different, the different seeds can result different hashcode

three old canary annotations are reused
canary-weight
canary-by-header
cookie

Compatibility
won't harm other canary strategies
but if canary-consistency is configured, other strategies won't work

[k8s-ci-robot]

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[k8s-ci-robot]

PR needs rebase.

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[k8s-ci-robot]

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[k8s-ci-robot]

Hi @2339478391. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[longwuyuan]

The expectations from the canary feature are mostly being met for the large number of users of canary feature.

Adding new features is not being considered on the ingress-controller because the focus is to be secure by default while being compliant to the K8S ingress-api specs. The project is actually deprecating some features as its not a improvement to maintain & support features that impact security, stability & other such deliverables.

I don't think the project should implement the changes proposed here.